The objectives of the proposed research are to elucidate the functional roles of cyclic GMP-dependent protein kinase, its stimulatory modulator, and stimulatory modulator-requiring, cyclic nucleotide-independent protein kinase in normal and malignant cell proliferation. The experimental models to be employed are: Morris hepatomas (vs. normal livers) in rats, and regenerating livers (vs. sham-operated livers and normal livers). Attempts will be made to seek, characterize or identify possible changes in patterns, localizations and poperties or species of cyclic GMP-dependent protein kinase, its stimulatory modulator, and stimulatory modulator-requiring, cyclic nucleotide-independent protein kinase, as well as those of endogenous substrate proteins of the two enzymes, in cells undergoing proliferation. The above parameters will be compared to those obtained for cyclic AMP-dependent protein kinase and its inhibitory modulator.